JPS591178B2 - Extrusion die for multilayer film production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a multilayer film (
The present invention relates to an extrusion die for manufacturing (including sheets with a thickness of 0.25 mm or more).

As an extrusion die for manufacturing a multilayer film consisting of three layers, a first distribution conduit that guides the first film raw material supplied from the first extruder vertically downward to the discharge port, and a first distribution conduit for guiding the first film raw material supplied from the first extruder to the discharge port, and the first film raw material supplied from the second extruder are provided. and second and third distribution channels for guiding the second film raw material to opposite sides of the first distribution channel, the width of the first distribution channel and the width of the second and third distribution channels being equal to each other. An extrusion die configured to have different widths is known (see Japanese Utility Model Publication No. 52-37659).

The above-mentioned known extrusion die forms an unstretched multilayer film consisting of three layers so that the width of the front and back layers made of the same raw material is wider or narrower than the width of the intermediate layer made of other raw materials (
(See Figure 6, T), the front and back two layers Q. By gripping only r or the intermediate layer p with a tenter clip, the cutting scraps obtained by cutting both ends after stretching and heat setting are converted into cutting scraps made of pure single synthetic resin of either the first or second film raw material. The aim is to collect and reuse cutting waste. However, the unstretched multilayer film F manufactured by the above-mentioned known extrusion die
, both ends have two layers Q, front and back. Since it consists of only r or intermediate layer p, and the intermediate part consists of three layers, the thickness of both ends and the middle part is different, and the thickness changes rapidly at the boundary between both ends and the middle part, which makes it difficult to draw with a tenter. In this case, stress is concentrated at the boundary area, which tends to cause breakage, and only the area near the boundary area is greatly stretched, resulting in insufficient and uneven stretching of the intermediate part that should become the final product. The drawback was that film characteristics could not be obtained.

Therefore, when stretching with a tenter, it is a reality that the intermediate part consisting of three layers is held near the end with a tenter clip, and in this case, it is impossible for the cutting waste to become a mixture of the first and second film raw materials. As this is unavoidable, the original purpose of collecting and utilizing cutting waste cannot be achieved. This invention provides an extrusion die for producing a multilayer film in which each layer has the same width as shown in FIGS. In addition, it is possible to produce an unstretched multilayer film whose composition at both ends is so high that the cutting waste can be recovered and used.

That is, the present invention includes two or more distribution channels each consisting of a manifold and a narrow passage following the manifold, and the lower ends of the distribution channels are respectively connected to the soil ends of the merging channel, and the lower ends of the merging channel are connected to each other. In an extrusion die for producing a multilayer film in which a multilayer film is extruded from a discharge slit, the above-mentioned distribution channel and merging channel are formed to have equal widths, and at least one distribution channel is provided with the distribution channel. This is an extrusion die for producing a multilayer film characterized by inserting a resistance rod which is narrowed to form different gaps at both ends and a middle portion.

Both ends of the above-mentioned distribution channel correspond to both ends of the multilayer film held by tenter clips when stretching the multilayer film with a tenter, and the preferred width thereof is 1 on one side.
0 to 200 mm1, particularly preferably 30 to 120 mm.

If the above-mentioned width is less than 10 mm on one side, the width of the end portion will also shrink as the width shrinks during melt extrusion and roller stretching of the obtained multilayer film, and the width of the end portion will be insufficient during tenter stretching. 2007!
If the length exceeds 1 m, the width of the middle part, which should become the final product, becomes narrow and there will be a lot of waste. A transition part can be provided between the ends and the middle part, and the preferred width of this transition part is 3 to 100 m71L. The resistance rods described above are inserted into the manifold of the distribution conduit or into the slot passageway directly below the manifold.

The resistance rod inserted into the slit passage is preferably one shaped like a tie yoke, which is conventionally used to adjust or close the gap in the slit passage. In this case, the surface of the resistance rod extending into the slit passage is formed in a shape that makes the gap between both ends and the middle part of the slit passage different. The narrower gap of the slit passage is 1 to 90%, preferably 1% of the wider gap.
It is set between 0 and 80%. If the gap on the narrower side is less than 1% of the gap on the wider side, film breakage will occur during stretching;
If it exceeds %, the purity of the cutting waste will decrease. On the other hand, the resistance rods inserted into the manifold are inserted into both ends of the manifold from the sides, and have a needle valve shape whose bases are fixed to side plates that close openings at both ends of the manifold. This needle valve-shaped resistance rod narrows the gap between the manifolds except for the middle part, and its cross-sectional shape is approximately similar to the cross-sectional shape of the manifold, or is circular, oval, polygonal, etc. The gap between both ends is set to be 1 to 95% of the gap between the ends. Note that the needle valve-shaped resistance rod can be integrally provided with a thin plate portion that is inserted into the narrow passageway. The above-mentioned tie-yoke single-shaped resistance rod allows the gap at the middle part of the distribution channel to be made wider or narrower than at both ends, depending on its shape setting. While the rod cannot have both ends wider than the middle, its structure becomes simpler.

Therefore, depending on the cross-sectional shape of the desired multilayer film,
The above-mentioned one-piece or needle-shaped resistance rod is selectively used. The resistance rod is inserted into at least one distribution channel, and may be inserted into other distribution channels as necessary. For example, when manufacturing a multilayer film consisting of three layers in which the front and back layers are made of the same material and the middle layer is made of different materials, if the thickness of the middle layer at the middle part in the width direction is relatively thin, the distribution channel for the middle layer may be By inserting a resistance rod in the form of a needle valve or a tie yoke, both ends of the intermediate layer can be made thinner than the middle part.
Furthermore, when the front and back layers are relatively thin, it is possible to make both ends of the intermediate layer thicker than the intermediate portion by inserting a resistance rod in the form of a tie yoke into the distribution channel for the intermediate layer. and,
By appropriately inserting resistance rods in other distribution channels, the thickness of the obtained multilayer film can be made uniform in the width direction. Below, an example in which a resistance rod in the shape of a tie yoke is inserted into the distribution path for the intermediate layer, and a resistance rod in the shape of a needle valve is inserted in the distribution path for the front and back two layers is shown in Figures 1 to 3. I will explain.

The extrusion die 1 includes a coupling adapter 2, a front body 3 and a rear body 4 in contact with the lower surface of the coupling adapter 2, a fixed lip 5 in contact with the lower surface of the front body 3, and an L-shaped joint in contact with the lower surface of the rear body 4. The metal fitting 6, the beam-like metal fitting 7 that contacts the inside of the L-shaped metal fitting 6, the adjustment lip 8 that contacts the lower surface of the beam-like metal fitting 7, and the left and right side plates 9, 10 are connected to each other by a large number of bolts (not shown). ), and a heater (not shown) for keeping warm is attached around the periphery.

A first distribution conduit 11 consisting of a first manifold 11a, a first slit passage 11b, and a pressure equalization chamber 11c spans the entire width at the joint between the front body 3, the rear body 4, and the L-shaped coupling fitting 6. It will be deleted. At the joint between the front main body 3 and the fixed lip 5, there is a second horizontal distribution channel 1 consisting of a second manifold 12a and a second narrow passage 12b.
2 is cut across the entire width and merges with the lower end of the first distribution channel 11. Further, at the joint between the L-shaped coupling fitting 6 and the beam-shaped coupling fitting 7, a third distribution pipe consisting of a third manifold 13a and a third narrow passage 13b is provided opposite to the first distribution conduit 11. A guide path 13 is cut out. Furthermore, a merging channel 14 that follows the merging point of the first to third distribution channels 11, 12, and 13 is cut at the joint between the fixed lip 5, the beam-like coupling fitting 7, and the adjusting lip 8. The lower end of the merging channel 14 forms a discharge slit 14a. Note that the opening ends in the width direction of the first to third distribution channels 11, 12, 13 and the merging channel 14 are closed by side plates 9, 10. The coupling adapter 2 is provided with a first inlet 15 communicating with a first extruder (not shown) and a second inlet 16 communicating with a second extruder (not shown). There is.

The above-mentioned first introduction port 15 is connected to the first manifold 11a by a first introduction path 17 that is formed in a communicating manner at the center of the coupling adapter 2 and at the joint between the front body 3 and the rear body 4. Ru. On the other hand, the second introduction port 16 is connected to the second manifold 12a by a second introduction path 18 that is connected to the front part of the coupling adapter 2 and the center of the front main body 3. The third manifold 13a is connected to the third manifold 13a by a third introduction path 19 bored in the rear part of the rear body, the center part of the rear main body 4, and the horizontal part 6a of the L-shaped coupling fitting 6. A square groove 4a is cut in the width direction at the lower end of the rear main body 4 facing the first narrow passage 11b, and a resistance rod 20 in the form of a tie yoke is inserted into this square groove 4a so as to be slidable back and forth.
As shown in FIG. 2, the front surface 20a of the resistance rod 20 has linear ends 20b, 20b forming a wide gap with the linear wall surface 3a of the front main body 3, and a narrow gap forming therebetween. It consists of a linear intermediate portion 20c, and transition portions 20d, 20d connecting the end portion 20b and the intermediate portion 20c. Further, a large number of screw holes 20f are bored in the rear surface 20e of the resistance rod 20, and the rear main body 4 is inserted into the screw holes 20f.
Asiast bolt 21 passing through round hole 4b drilled in
The tips of the two are screwed together. A groove 21b is cut around the head 21a of this Asiast bolt 21.
1b is engaged with a stopper 22 fixed to the rear surface of the rear main body 4, and by rotating the Asiast bolt 21, the resistance rod 20 is slid in the front-rear direction. Needle valve-shaped resistance rods 23 are inserted into both ends of the second distribution conduit 12 and the third distribution conduit 13 described above. This needle valve-shaped resistance rod 23 has a rod-shaped portion 23a inserted into the manifolds 12a, 13a having a relatively wide space, and a thin plate portion 2 inserted into the narrow passageways 12b, 13b having a narrow space.
3b, and the inner end 23c is formed into an inclined surface that does not disturb the flow of the resin, as shown in FIG. The base portion 23d of the resistance rod 23 is fixed to the inner surfaces of the side plates 9 and 10 with bolts 24. A square groove 7b is cut in the width direction at the lower end of the beam-like coupling fitting 7 facing the above-mentioned merging guideway 14, and a tie cover 25 is inserted into this square groove 7b.

This tie yoke 25 is a normal yoke cover whose front face facing the merging channel 14 is formed straight in the width direction, and passes through the vertical part 6b of the L-shaped coupling fitting 6 and the round hole of the beam-shaped coupling fitting 7. It is screwed onto the tip of the Asiast bolt 26. The head of the Asiast bolt 26 is engaged with a stopper 27 fixed to the front surface of the L-shaped coupling fitting 6.
By rotating the Asiast bolt 26, the gap between the merging channels 14 can be adjusted. Further, the adjustment lip 8 fixed to the lower surface of the beam-like coupling fitting 7 is screwed onto the tip of an Asiast bolt 28 passing through the L-shaped coupling fitting 6, and the head of this Asiast bolt 28 is attached to the stopper 27. engaged. This adjusting lip 8 is slid in the front and back direction by loosening the connecting bolt between the adjusting lip 8 and the beam-like coupling fitting 7 and rotating the Asiast bolt 28, thereby closing the gap between the discharge slits 14a. It is something to be adjusted. In the above structure, the first thermoplastic synthetic resin of the first extruder is supplied to the first inlet 15, and the second thermoplastic synthetic resin of the second extruder is supplied to the second inlet 16, A multilayer film p consisting of three layers, including a first thermoplastic synthetic resin as an intermediate layer p (see FIG. 4) and a second thermoplastic synthetic resin as a surface layer q and a back layer r, is extruded from the discharge slit 14a. .

Since the resistance rod 20 is inserted into the first distribution channel 11 in which the intermediate layer p is formed, the intermediate layer p is formed to be thick at both ends and thin at the middle. Note that the average thickness of the intermediate layer p is adjusted by rotating the Asiast bolt 21. In addition, needle valve-shaped resistance rods 23 are inserted into the second distribution channel 12 and the third distribution channel 13 that form the surface layer q and the back layer r, so that the surface layer q and the back layer r are , both ends are thin and the middle part is thick.
Therefore, by appropriately setting the shape of the resistance rods 20 and 23, it is possible to make the thickness of the multilayer film p substantially uniform over the entire width and avoid stress concentration during stretching, and also to avoid stress concentration after stretching. Both end portions and the transition portion to be cut and removed can be made of high-purity materials containing a large amount of the first thermoplastic synthetic resin, making it possible to recover and utilize the cutting waste. In the above embodiment, the third introduction path 19 is separated from the second introduction port 16, and the third extruder is connected to the third introduction path 19, so that the surface layer q and the back layer r are heated to different temperatures. It can be made of plastic synthetic resin.

In addition, a needle valve-shaped resistance rod 23 is provided in the first distribution channel 11.
, or by inserting a resistance rod 20 in the form of a tie yoke that widens the gap at both ends and narrows the gap in the middle, and connects the second distribution conduit 12.
When a resistance rod 20 in the form of a tie yoke is inserted into the third distribution conduit 13 to widen the gap between the ends of the distribution conduits 12 and 13 and to narrow the middle part, the multilayer film p shown in FIG. 5 is obtained. . In addition, in the multilayer film p shown in FIG. 4, when the thickness of the intermediate portion of the surface layer q and the back surface layer r is made very thin, as described above, the second distribution channel 1 of Example 1
Needle valve-shaped resistance rods 23 of the second and third distribution channels 13
can be omitted. In this case, the total thickness of the multilayer film p is somewhat thicker at both ends than at the middle, but the difference is small and there is no practical problem. Furthermore, in the multilayer film p shown in FIG. 5, if the thickness of the intermediate portion of the intermediate layer p is made very thin, the resistance rod 20 in the form of a tie-cover in the first distribution guide path 11 can be omitted. In addition, when inserting the resistance rod 20 in the shape of a tie yoke into the second distribution guide path 12 and the third distribution guide path 13, it is preferable that the second distribution guide path 12 and the third distribution guide path 13 be inclined. Further, in the embodiment described above, the needle valve-shaped resistance rod 23 is provided so as to be slidable in the width direction, so that the insertion length into the distribution channels 12 and 13 can be freely adjusted. Further, the needle valve-shaped resistance rod 23 can have an inner end 23c formed into a plane perpendicular to the width direction, and the length of the thin plate portion 23b can be set within a range where the tip thereof does not protrude into the merging channel 14. It can be set arbitrarily, and the thin plate portion 23b can be omitted. Further, although the above embodiment is an extrusion die for producing a multilayer film consisting of three layers, it is of course possible to produce a multilayer film having two or more layers by increasing or decreasing the number of distribution channels. As explained above, this invention
Since each layer of the unstretched multilayer film has the same width, and each layer has a different thickness at both ends and the middle part in the width direction, the cutting waste after stretching can be collected and reused. It is possible to produce a high-quality multilayer film in which both ends are highly purified to a certain extent, and there is no stress concentration during tenter stretching, so that film breakage and uneven stretching do not occur.

[Brief explanation of the drawing]

1 is a vertical cut side view of an embodiment of the present invention, FIG. 2 is a plan view cut horizontally along the - line of FIG. 1, FIG. 3 is a plan view cut horizontally cut along the - line of FIG. FIG. 5 is a vertically cut front view of a multilayer film produced according to the present invention, and FIGS. 6 and 7 are vertically cut front views of conventional multilayer films. 1...Extrusion die, 11a, 12a, 13a.
...Manifold, 11b112b113b...
... Slit passageway, 11, 12, 13... Distribution channel, 14... Merging channel, 14a...
Discharge slit, 20, 23...Resistance rod, 20b...
...Both ends, 20c...Middle part, 20d.
...Transition part, p...Multilayer film.

Claims (1)

[Scope of Claims] 1. Two or more distribution channels each consisting of a manifold and a narrow passageway following the manifold, the lower ends of the distribution channels being connected to the upper ends of the merging channel, respectively, so that the lower end of the merging channel is connected to the lower end of the merging channel. In an extrusion die for producing a multilayer film in which a multilayer film is extruded from a discharge slit of 1. An extrusion die for producing a multilayer film, characterized in that a resistance rod is inserted to narrow the distribution channel and form different gaps at both ends and in the middle. 2. A transition part is provided between both ends of the distribution conduit and an intermediate part, and the width of the end part is 10 to 200 mm on one side, and the width of the transition part is 3 to 100 mm. Extrusion die for multilayer film production. 3. For manufacturing a multilayer film according to claim 1 or 2, wherein the resistance rod narrows the narrow passageway on the lower side of the manifold at different ratios at both ends and in the middle part over the entire width. extrusion die. 4. The extrusion die for producing a multilayer film according to claim 3, wherein the resistance rod is provided so that the depth of entry into the narrow passageway can be freely adjusted. 5. The extrusion die for producing a multilayer film according to claim 1 or 2, wherein the resistance rod is a needle valve type that is inserted into both ends of the manifold from the side. 6. The extrusion die for producing a multilayer film according to claim 5, wherein the resistance rod is provided so that its penetration depth into the manifold can be freely adjusted. 7. Multilayer film production according to claim 1, wherein a resistance rod is inserted into each of the plurality of distribution channels, so that the multilayer film extruded from the discharge slit has approximately the same thickness in the width direction. extrusion die. 8 Resistance rods are inserted into the narrow passageways at the bottom of some manifolds to widen the gap at both ends and narrow it in the middle, while in other manifolds short needle valve-shaped resistance rods are inserted from the sides. An extrusion die for producing a multilayer film according to the appended claim 7.